New study confirms that e-cigarettes have minimal quantities of nitrosamines – authors do not report it as a conclusion


By Dr Farsalinos 

            A study published 3 months ago in Journal of Chromatography A confirms that e-cigarette liquids have minimal quantities of cancer-causing nitrosamines, however, authors failed to mention the comparable levels detected in tobacco cigarettes.

            Researchers tested 105 refill-liquids from 11 companies, available in the South Korean market. They used liquid chromatography–tandem mass spectrometry to measure the levels. In fact, they had to pre-concentrate the samples because trace amounts of nitrosamines were present.

            The results showed that the mean concentration of nitrosamines were 12.99 ± 18.23 micrograms per liter. This is about 13 nanograms per milliliter. The authors fail to present any data about the comparable levels of nitrosamines in tobacco cigarettes. So, we have to do the search ourselves. Stepanov and coworkers found that the levels of nitrosamines present in tobacco cigarettes were 3365 to 6260 nanograms per one cigarette. We should not forget that 1 milliliter of e-liquid is not equivalent to 1 cigarette; 1 ml of liquid is approximately 1/3rd to 1/4th of the average daily consumption. Therefore, by comparing daily intake of nitrosamines from smoking and e-cigarette, the difference would be much wider (in favor of e-cigarette). The same study by Stepanov reported that one nicorette gum has 2 nanograms of nitrosamines. I remind you that the maximum recommended daily use is 15 gums. So, you may get almost equal amounts of nitrosamines whether you use e-cigarette or pharmaceutical nicotine replacement therapy. Such levels can be considered harmless for humans.

            The authors mention that nitrosamines may be formed when liquids are heated. They mention the study by Schripp and coworkers to support that liquid can be heated to temperatures above 350oC and this can result in formation of nitrosamines. This is completely wrong and mis-informative, because Schripp used a thermographic camera to measure temperature of the electronic cigarette without the presence of liquid. This is completely different. When liquid is present, the electrical energy is not transformed into heat but is used for the process of evaporation. It is impossible for e-cigarette to reach to 350oC under normal conditions. It could happen when no liquid is present. Therefore, the authors’ statement that nitrosamines can be produced when liquid is heated to 350oC is wrong. Interestingly however, during the process of liquid chromatography analysis, they heated the liquid to temperatures up to 350oC (according to author’s statement - section 2.4 of the full text). Therefore, it is possible that some of the nitrosamines measured may come from this heating process, and their findings may in fact overestimate the true levels of nitrosamines.

            In conclusion, this is another study showing that nitrosamines are present in minimal (and probably clinically insignificant) quantities in electronic cigarette liquids. Once again, the authors fail to report the true message of this study by avoiding the obvious and important comparison with tobacco cigarettes.


Dr Farsalinos is a researcher at Onassis Cardiac Surgery Center in Athens-Greece and at Medical Imaging Research Center, University Hospital Gathuisberg in Leuven-Belgium. He is actively involved in research on e-cigarettes’ safety and risk profile.

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